A collaborative clinical trial to compare limited and extended fields of radiotherapy for patients with localized Hodgkin's disease has completed accession of 461 patients and is following these with special attention to survival, extension of disease, and complications of therapy. With 108 patients observed to 4 years survival, 83% and 84% survivals are seen for the 2 treatment groups, respectively. At no time interval up to 4 years is there a significant survival difference. Complications are more frequent and more severe after extended field treatment. Extension of disease in surviving patients is more frequent after limited fields. The proposed study will continue the follow-up of these patients to obtain estimates of effect at longer intervals. Nonexperimental observations are made with respect to prognostic significance of age, sex, histologic type, use of laparotomy in staging, use of greater or lesser extent of extended radiotherapy fields. Results to date indicate significant favorable effects of young age and nodular sclerosing histology. The female sex shows favorable survival with limited field therapy, but no sex difference is seen with extended fields.